Method for the targeted production of N-type conductive areas in diamond layers by means of ion implantation

ABSTRACT

The invention relates to the production of semiconductor elements made of diamond, diamond layers and diamond-like layers, which are doped using the ion implantation method and on which N-type conductive areas are also placed. According to the invention, silicium at a concentration of more than 0.1 atom % is implanted in the lateral and depth areas to be doped, in addition to the elements of the fifth main group known per se which are used in doping. The silicium can be implanted before or after the elements of the fifth main group are applied to the diamond substrate or in a step comprising both. When silicium is implanted after the ions of the elements of the fifth main group, regeneration can be carried out after each implantation or after the second implantation.

FIELD OF THE INVENTION

The invention relates to the production of semiconductor components ofdiamonds, diamond layers and diamond-like layers, which are doped bymeans of ion implantation and in which n-conducting areas are alsointroduced.

BACKGROUND OF THE INVENTION

It is generally known from semiconductor technology that silicon andsilicon carbides can be doped by means of ion implantation with elementsof the fifth main group and that n-conducting areas can be produced inthis way. The efforts, to use this method for doping diamonds, wereunsuccessful. Alterative methods for doping with, for example, lithiumor sodium, also did not lead to a satisfactory result (R. Kalish, IonImplantation in Diamond and Diamond Films: Doping, Damage Effects andtheir Applications, Applied Surface Science 117/118 (1997)558).

SUMMARY OF THE INVENTION

It is therefore an object of the invention to ensure a layer, whichsatisfies the respective requirements with regard to n-conductivity, indiamonds, diamond layers and diamond-like layers by means of ionimplantation.

The starting materials for the invention are diamonds, diamond layersand diamond-like layers, into which elements of the fifth main group areintroduced by means of ion implantation and which are annealed. Pursuantto the invention, silicon is implanted in addition to the elements ofthe fifth main group in the lateral and deep region, which is to bedoped, in a concentration of more than 0.1 atom percent. The silicon canbe implanted in the diamond substrate before or after the introductionof the elements of the fifth main group or in one process step togetherwith this introduction. If the silicon is implanted after the ions ofthe elements of the fifth main group are introduced, the annealing canbe carried out after each implantation or only once after the secondimplantation.

DETAILED DESCRIPTION OF THE INVENTION

The advantages of the invention consist therein that, due to thecomplete or partial conversion of diamond areas into silicon carbide,the deep donor states of the nitrogen (E_(c)−1.7 eV) become flat and,with that, electrically active donor states (E_(c)−0.08 . . . 0.14 eV)in the diamond. In addition, the graphite portions in the diamond, whichare caused by implantation damage and worsen the semiconductingproperties, are reduced. Because of the different energy gaps, hetero pntransitions are formed between the Si_(X)C_(1−X) areas (3C—SiC:E_(g)=2.3 eV) and diamond areas (E_(g)=5.5 eV), which have a series ofadvantages over homo pn transitions, such as a lower electron holerecombination rate. With that, a higher current amplification and ahigher limiting frequency are reached.

The invention is described in greater detail below by means of twoexamples.

EXAMPLE 1

A p-conducting diamond layer, doped with boron during the deposition andhaving a minimum thickness of 1 μm, is implanted in an area of 5×5 mm²at a temperature of 600EC with silicon ions (ion energy of 50 keV, anion dose of 1×10¹⁸ cm⁻²) for the synthesis of silicon carbide andsubsequently with nitrogen ions (ion energy of 20 keV and an ion dose of1×10¹⁵ cm⁻²) for n-doping. After the sample is annealed for 10 minutesat 1700EC, an approximately 50 nm thick n-doped silicon carbide layer,with a hetero pn transition to the diamond substrate, is formed in theimplanted region.

EXAMPLE 2

A natural diamond with insulating properties (Type IIa) is implanted at1000EC initially with boron ions (ion energy of 50 keV and an ion doseof 1×10¹⁶ cm⁻²), then with nitrogen ions (ion energy of 30 keV and anion dose of 5×10¹⁵ cm⁻²) and silicon ions (ion energy of 50 keV and anion dose of 5×10¹⁷ cm⁻²). After the sample is annealed for 10 minutes at1700EC, a pn transition between the n-conducting surface layer, which ispartially converted into silicon carbide, and the buried p-conductinglayer, is formed at a depth of about 50 nm.

What is claimed is:
 1. A method for the targeted production ofn-conducting areas in diamonds, diamond layers and diamond-like layers,comprising introducing ions of elements of the fifth main group andsilicon ions by ion implantation, in the lateral and deep region, whichis to be doped, in a concentration of more than 0.1 atom percent, toproduce ion implanted diamonds, diamond layers and diamond-like layers,and thermally annealing the ion implanted diamonds, diamond layers anddiamond-like layers.
 2. The method of claim 1, comprising introducingthe elements of the fifth main group and the silicon, respectively, inconsecutive order by an ion implantation process, into diamonds, diamondlayers and diamond-like layers.
 3. The method of claim 1 or 2,comprising introducing the elements of the fifth main group and thesilicon jointly by an ion implantation process, into diamonds, diamondlayers and diamond-like layers.
 4. The method of claim 1 or 2, whereinthe thermal annealing is carried out after each ion implantation.
 5. Themethod of claim 1 or 2, wherein the thermal annealing is carried outafter a second ion implantation.
 6. The method of claim 1 wherein thediamond layer to be treated is a p-conducting diamond layer doped withboron.
 7. The method of claim 1 wherein the elements of the fifth maingroup comprise nitrogen.
 8. The method of claim 6 comprisingsequentially introducing silicon and then nitrogen by ion implantationinto the boron doped diamond layer.
 9. The method of claim 6 comprisingintroducing silicon and nitrogen ions by ion implantation into the borondoped diamond layer.
 10. A material produced by the process of claim 1that is selected from the group consisting of diamond, diamond layersand diamond-like layers that comprise at least one n-conducting area.